The present invention relates generally to a rupture disc and a method of manufacturing the same and, more particularly, to a rupture disc having control scores associated with the concave or convex side of the disc to facilitate controlling the reversal pressure at which the dome of the disc will start to collapse.
Systems and vessels that contain a pressurized fluid often include rupture discs that relieve the system in the event of over pressurization. The discs are generally placed in a vent or pressure vessel to prevent flow of the fluid through the vent until the disc ruptures. Specifically, as a system becomes over pressurized and reaches a predetermined pressure, the disc ruptures to allow flow of the fluid through the venting system, thereby relieving the pressure within the system.
Rupture discs are commonly formed as a forward acting tension type disc or a reverse-acting rupture disc. Forward acting tension type discs may include a score line in the surface of the disc to ensure that the disc opens at a predetermined pressure and pattern of opening. Reverse-acting rupture discs may be formed in a dome shape with a rated reversal load or pressure under which the pressure of the system causes the disc dome to buckle or collapse and rupture. Accordingly, reverse-acting rupture discs require a selective adjustment of the rated reversal load or pressure to satisfy individual rupture values specified by customers.
Many methods have been used in the prior art to control the rated reversal load or reversal pressure. For example, protrusions or indentations can be formed on the convex side of the disc dome at various heights, lengths, and locations to vary the reversal load of the disc dome. These protrusions and indentations result in a non-smooth process surface which has been perceived as not desirable for a system that is to be kept in a sterile condition. In other references such as U.S. Pat. Nos. 6,241,113 and 6,006,938, issued to Mozley et al., an indentation or deformation is deliberately formed in the dome of the disc to initiate reversal at the deformation. The height of the deformation is selected to control the reversal pressure of the dome.
U.S. Patent Application Publication 2006/0237457 describes a method of forming an indentation in the dome, wherein the indentation includes a predetermined extent and depth. The indentation is then removed by returning the metal of the indentation to its initial position thereby restoring a smooth surface. As a result of the removal of the indentation, the local region subject to such indentation has mechanical and material characteristics different from the rest of the disc material so that, by controlling the formation and removal of the indentation, this process controls the reversal load of the disc. However, such disc formation requires multiple steps with an associated additional variation in forming and returning the indentation to its original smooth condition.
Accordingly, there is a need for a mechanism and method to control the reversal pressure of a rupture disc that includes minimal steps and that is subject to less variation while maintaining the sanitary conditions necessary for many rupture disc applications.